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Welcome to the STEREO Learning Center
How does 3d work?
Most human beings use what is known as binocular vision to perceive depth and see the world
in 3D. The binocular vision system relies on the fact that we have two eyes, which are
approximately 3 in apart. This separation causes each eye to see the world from a slightly
different perspective. The brain fuses these two views together. It understands the
differences and uses them to calculate distance creating our sense of depth and ability to
A simple way to understand this principle is to hold your thumb up at arms length and close
one eye. Then try closing the other eye. As you switch between open eyes you should see your
thumb "jumping" back and forth against the background. To see how much of a difference
the binocular vision system makes, have a friend throw you a ball and try to catch it while
keeping one eye closed.
If you've ever used a View-Master or a stereoscopic viewer, you have seen your binocular
vision system in action. In a View-Master, each eye is presented with an image. Two cameras
photograph the same image from slightly different positions to create these images. Your eyes
can then correlate these images automatically because each eye sees only one of the images.
There are many ways to view 3D images:
- Stereo Pairs (stereoscope: separate display for each eye)
- Shutter glasses (most common method)
- Color filter glasses (used in some old 3D movies)
- Polarizing glasses (used in some modern 3D movies)
Typical stereo pair images are two separate images of the same object taken a few inches
apart. In this method, the two images are not interlaced but rather presented side by side
(left eye image on left and right eye image on right). The images are directly viewable using
parallel "free-viewing" glasses which allow each eye to only see its correstponding
LCD shutter glass method
In the LCD shutter glass 3D display, the left and right images are alternated rapidly on
the monitor screen. When the viewer looks at the screen through shuttering eyewear, each shutter
is synchronized to occlude the unwanted image and transmit the wanted image. Thus each eye sees
only its appropriate perspective view. The left eye sees only the left view, and the right eye only
the right view.
Color filter glasses
Color filter glasses are one of the oldest methods of viewing 3D images or movies. The
system works by feeding different images into your eyes. The different color filters allow
only one of the images to enter each eye, and your brain does the rest. There are two color
filter systems: Red/Blue and Red/Green.
This method is more comonly used in today's 3D movie projections. The audience must wear
special glasses which have two polarizing lenses which have their polarization directions
adjusted to be 90 degrees different. This makes is possible that left eye sees it's picture
without problems but everything ment to right eye (sent out at different polarization) seems
to be black. Same applies also to right eye.
Last Revised: Wednesday, 05-Dec-2012 16:15:41 EST
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